This study will evaluate the effectiveness of the bioequivalent product of Ceredase, Cerezyme, in treating skeletal manifestations of the disease. It will longitudinally evaluate the effectiveness of Cerezyme in achieving improvements in the skeleton with doses of 60 U/kg/2 weeks after 12, 24, 36 and 48 months of therapy. Many physicians adjust dosage based on responses in hematologic and visceral organ parameters without adequate information on bone response. It would be important to also determine that a response in the skeleton has been achieved before a dose adjustment is considered. This dose management approach based on achievement of specified bone responses will be studied. In addition, this study will evaluate if doses lower than the initial 60 U/kg/2 weeks regimen will maintain skeletal improvements expected to be achieved with prolonged administration of 60 U/kg/2 weeks. It will also allow for comparison of skeletal responses in patients who are maintained on 60 U/kg/2 weeks for greater than 24 months to those who have dose reductions after 24 months.